Muscular layers refer to the different layers of muscle tissue found in various organs and structures within the body. These layers are primarily composed of smooth, cardiac, or skeletal muscle, each serving distinct functions. For example, the smooth muscle layers in the walls of the digestive tract help move food through the system, while skeletal muscle layers enable voluntary movements. In the heart, the cardiac muscle forms a thick layer called the myocardium, which is responsible for pumping blood. The arrangement and thickness of these muscular layers vary depending on the organ's function, allowing for efficient movement and support throughout the body.